House Extension Drawings in Harrow on the Hill |

No Article 4 Direction covers Harrow, which keeps the Harrow on the Hill permitted-development route open on unlisted houses. The Harrow on the Hill setting is Georgian and Victorian conservation hilltop, which shapes what passes near St Mary's Church. Conservation status changes the Harrow on the Hill route entirely — Harrow on the Hill being the usual case among the 29 designations in Harrow. The designation map is read street by street in Harrow on the Hill.

Knowing how Article 4 directions apply to your HA1 address is the first thing we establish. On Harrow on the Hill stock the constraint is physical before it is planning: the georgian and victorian houses fixes the rear wall line and the St Mary's Church roofline caps the ridge. The borough policy layer over every HA1 address is set out on Harrow planning. The Harrow on the Hill survey then carries into loft conversion drawings in Harrow on the Hill if the project runs on to construction.

Validation at London Borough of Harrow is the first delay a Harrow on the Hill applicant meets. The first visit to Harrow on the Hill is a measured survey — every room, every opening, every level change recorded on site.

Statutory periods: 8 weeks from validation for a householder application, 13 weeks for a major scheme, 6 weeks for prior approval with a 21 days neighbour consultation, and 5 weeks for a full plans building control submission. A party structure notice requires one month notice and two months where excavation is involved.

After validation a Harrow on the Hill application is allocated to an officer, who will visit the HA1 address. Each HA1 drawing carries the address, scale, north point and revision.

A Harrow on the Hill scheme that respects the 45-degree line rarely draws a sustained objection. Existing structure in the georgian and victorian houses is identified at survey, not guessed later.

Shared walls are the norm in Harrow on the Hill; the notice period is not optional. Once consent is granted, architectural drawings follows for the HA1 property.

Harrow on the Hill is characterised by georgian and victorian houses, listed buildings, concentrated across HA1 in the Harrow / Harrow on the Hill area. On Harrow on the Hill streets the georgian and victorian houses sets the structural sequence — what can be opened up, where the load goes, how deep you can build. Reading that across to Harrow on the Hill stock: georgian rear elevations here are usually the listed or locally listed face of the building, so a glazed link and a lightweight rear addition tend to fare better than a full-width box. That is drawn out in the Harrow on the Hill proposed section. Harrow Council judges massing against the established Harrow on the Hill rhythm — the eaves and ridge lines running past St Mary's Church.

A Harrow on the Hill basement stands on its drainage and party wall evidence. Survey data from the Harrow on the Hill property flows straight into planning permission for HA1 properties or building regulations drawings without a second site visit.

What the Harrow on the Hill drawing pack contains

Here is what a HA1 instruction actually produces.

• existing and proposed ground-floor plans for the Harrow on the Hill property
• proposed rear elevation
• long section through the extension
• site and block plans
• party wall position drawing

Local landmarks that shape a Harrow on the Hill application

• Northwick Park — shared flank walls, so Northwick Park party structure notices go out before work starts.
• Sudbury Hill — shared flank walls, so Sudbury Hill party structure notices go out before work starts.
• St Mary's Church — massing on adjoining HA1 plots is tested against it.
• Harrow School — proposals within its setting are drawn with the context elevation included.
• St Dominic's Sixth Form College — massing on adjoining HA1 plots is tested against it.
• The John Lyon School — proposals in its setting are drawn with the Harrow on the Hill context elevation.
• Harrow School — proposals within its setting are drawn with the context elevation included.

Getting to a Harrow on the Hill survey

Surveyors travel to HA1 addresses from the studio; the nearest stations are Harrow-on-the-Hill station, Harrow-on-the-Hill, South Harrow. Appointments are booked in Harrow on the Hill on weekdays and Saturdays, and the measured survey of a standard georgian and victorian houses takes two to three hours.

Where Harrow on the Hill sits

on Ordnance Survey grid reference TQ155865, inside the Harrow West parliamentary constituency. That is the reference the Harrow on the Hill site plan is drawn over. Source.

Practical detail for a Harrow on the Hill submission: the closest stations to a HA1 site are Harrow-on-the-Hill station and Harrow-on-the-Hill and South Harrow; correspondence uses HARROW; dialling code 020. Site plans are drawn to the address as Harrow Council holds it.

Harrow on the Hill postcode coverage

Harrow on the Hill work spans HA1 (Harrow / Harrow on the Hill), which Harrow on the Hill holds on its own — the designations change with the district line.

Streets and stations in Harrow on the Hill

Harrow on the Hill addresses we have drawn run to Northwick Park and Sudbury Hill. most Harrow on the Hill sites are within walking distance of Harrow-on-the-Hill station or Harrow-on-the-Hill or South Harrow.

Areas we cover around Harrow on the Hill

Harrow on the Hill sits in a patch that also takes in North Harrow (HA2), South Harrow (HA2), Uxbridge (UB8), Ruislip (HA4), Northwood (HA6), Hayes (UB3, UB4), and we work all of it as far as the Hillingdon boundary.

You know the number before the surveyor is booked. The fee follows the building. On Harrow on the Hill stock that means party walls, levels, and the Harrow on the Hill heritage question.

Statutory application fees are set by regulation, not by the council: £548 householder, £610 for a new dwelling, £274 for a lawful development certificate, £249 for prior approval.

On a HA1 submission the statutory fee goes straight to London Borough of Harrow. London planning approval-rate dataset · Harrow planning · the London house extension drawings pillar page · house extension drawings in North Harrow.

The technologist drawing your Harrow on the Hill scheme is MCIAT chartered — the professional body for technical design and building-regulations competence. Not every Harrow on the Hill scheme is clear-cut. Where Harrow on the Hill or the Harrow School setting is in play, Harrow Council pre-application advice comes before the HA1 submission.

Drawings are produced by chartered members of the Chartered Institute of Architectural Technologists (MCIAT), the professional body for technical design and building-regulations competence. First-time approval across our London caseload is 98%. Statutory fees shown are those in force in England in 2026 under the Town and Country Planning (Fees for Applications) Regulations. Confirm your local authority at gov.uk and submission requirements on the Planning Portal. Studio: 71–75 Shelton Street, London WC2H 9JQ.

We will tell you if a Harrow on the Hill project does not need us. This Harrow on the Hill page was reviewed in August 2026.